292 THE POPULAR SCIENCE 3I0NTHLY 



In general, geographers consider Lassen Peak as marking approxi- 

 niatel}- the southern end of the Cascade Eange, and as being the last of 

 that series of great volcanic cones of which Kainier, Adams, Hood, 

 Three listers, Mazama, Pit and Shasta are familiar examples. To the 

 southeast of Lassen the topographic gap of the Feather Eiver separates 

 the Cascade Range from its correlative, the Sierra Nevada, which ex- 

 tends four hundred miles farther to Tehachapi Pass, but whose lofty 

 peaks owe their height primarily to uplift rather than to volcanic up- 

 building. 



The southern fifty miles of the Cascade Eange extending north- 

 westerly toward Shasta from the North Fork of the Feather River is a 

 great volcanic ridge, about twenty- five miles wide. This ridge is studded 

 M-ith numerous minor volcanic cones culminating in Lassen, the domi- 

 nating peak, which is guai'ded by a nunil)er of other major cones rising 

 to heights varying from seven thousand to nine thousand feet above the 

 sea. Past volcanic phenomena of the Lassen Peak region in recent 

 geologic time have been made familiar to readers through J. S. Diller's 

 well-kiinwii roi)ort,- which descril)es with considerable detail the Cinder 

 Cone, ton miles northeasterly from the main peak, from the base of 

 which the latest lava flow issued. Until the present outbreak, despite 

 our knowledge of the Cinder Cone lava flows, it has been tacitly assumed 

 in physiographic literature that Lassen Peak belonged to the class of 

 extinct volcanoes, although the following statement by Diller in the 

 folio just quoted shows clearly that twenty years ago he did not consider 

 the volcano entirely extinct. 



The latest volcanic eruption in tlie Lassen Peak district, ami possibly the 

 latest in the United States south of Alaska, oecured at the Cinder Cone about two 

 hundred years a^o. Soiiie of the trees killed at the time are still standing. The 

 lava, although very viscous, spread more than a mile from the vent and formed 

 a huge tabular pile which extends across a little valley. The lava dam thus 

 formed developed Snag Lake, Avhieh contained stum[is of some of the trees 

 drowned at the time the lake originated. 



That volcanic activity is not yet extinct in the Lassen Peak district is shown 

 by the presence of numerous solfataras and hot springs. At Bumpass's Hell, 

 near the southern base of the peak, there are boiling nuid pools and vigorous, 

 solfataric action. Near by, at the head of Mill Creek, the sulphur deposited by 

 such action is so abundant that attempts have been made to mine it. Similar 

 phenomena occur in Hot Springs Valley and at Lake Tartarus and the Geyser, 

 near Willow Lake. The Geyser is much less vigorous than formerly, and now 

 the column of water rises scarcely a foot above its pool. 



Previous to the present activity of Lassen Peak there had been 

 numerous indefinite reports of eruptions witnessed by the Indians in that 

 vicinity shortly before the coming. of the white settlers. The most defi- 

 nite of these reports is given in a recent letter from Dr. J. W. Hudson, 

 of Ukiah, California. 



2 Lassen Peak Polio, U. S. Geol. Survey, 1S94. 



